The present invention relates to a storage system and to a management method for such a storage system, the storage system having a disk controller and an iSCSI device connected to the disk controller by a network. More particularly, the present invention relates to a format for managing storage connections on the network.
As IT becomes more widespread and entrenched, users continue to seek greater data storage capacity. Because of this, there are many cases where more data storage is necessary than the capacity originally installed in a storage system.
FIG. 8 shows an example of the overall construction of a conventional disk controller and storage system. In the conventional system shown in FIG. 8, a management program 235 on an SVP (Service Processor) 230 responds to an operation input to issue an instruction to a control program 217 and to a device list 218 located inside a disk controller 210 to register a new storage as a storage to be governed by the disk controller 210 itself and to connect a corresponding new magnetic disk 220 to a back end FC I/F 213, thereby achieving extension of the storage capacity.
In another method for increasing the storage capacity, instead of the magnetic disk 220, FC heterogeneous storage 227 having an FC device 225 is connected. Here, the term “storage” refers collectively to magnetic disks, magnetic tape, etc. The term “Heterogeneous storage” refers to any storage medium that the disk controller does not manage directly. Also, “FC” is an abbreviation for Fiber Channel. An example of an FC storage system is illustrated in an IBM white paper called “IBM Storage Tank™, A Distributed Storage System”, dated Jan. 24, 2002.
As shown in FIG. 8, when making a remote copy or effecting a backup of data, the storage where the remote copy is to be made does not necessarily have to be recognized by the disk controller as a storage governed by the disk controller 210 itself. Therefore, it is also possible to use a SAN (Storage Area Network) 250 to connect a heterogeneous storage 229 to a front end FC I/F 212 via an FC device 260. An example of such a construction is disclosed in U.S. Pat. No. 6,092,066.
On the other hand, in an IP network, transmissions can only be performed in accordance with TCP/IP protocol, for example. Therefore, in order to directly send SCSI protocol, which is common for a disk unit I/O, to the disk unit, a new protocol is necessary to piggyback common SCSI commands and the like onto the data portion of an IP frame. A representative example of this new protocol is iSCSI protocol.
An example of a storage system using iSCSI is disclosed in U.S. Pat. No. 5,996,024. This type of iSCSI I/F can transmit information about a magnetic disk, which is a target, to the disk controller, which is an initiator.
In a storage system using the FC I/F as described above, the network is closed inside the disk controller. Therefore, since it is possible to learn the status of everything, including the status of the FC heterogeneous storage and the status along the route thereto, it is possible to select the optimum storage when recording data.
However, in the FC I/F storage system described above, it is not possible to connect an IP network and an ISCSI heterogeneous storage that are spread widely around the world. Therefore, in order to create a network on an IP-network scale, it is necessary to set up a separate network with just the FCs. Furthermore, management methods used on IP networks cannot be simply transferred and used on a storage system using the FC I/F described above.
In order to add more storage using the FCs and a SAN, as disclosed in U.S. Pat. No. 6,092,066, it is necessary to establish the SAN network separately from the general IP network. This creates problems of increased equipment costs and management costs.
On the other hand, with an iSCSI I/F using an IP network, the iSCSI storage can be connected as the target, but only information about the target can be transmitted. Therefore, it is not possible to obtain information about the performance of the network leading to the iSCSI storage, or information about security, costs, or other such information about the IP network. Therefore, there is a problem in that it has not been possible to connect optimally to an iSCSI heterogeneous storage in a way which takes the status of the network into consideration.